Pool Cleaners commonly comprise of an enclosed hollow body that travels on wheels or tracks on the relative horizontal swimming pool surfaces; at least one brush to sweep the surfaces; at least two motors one of which drives the body on floor or walls; a pump motor that is positioned in a hydraulic system that draws water and debris from a bottom inlet opening in the said body where the said inlet is near or close to the travelled surfaces; said liquid passes through a filtering media and is subsequently ejected from the body from an upper positioned outlet opening.
The drawing through the bottom end of the body and the expelling of the water at the top end creates a negative pressure force at the bottom end to maintain the vehicle in contact with the underwater surface. Such a hydraulic system makes use of the suction port at the lower end of the body that also forms a negative pressure inside the body of the pool cleaner also called a vacuum pressure force.
The vacuum pressure force at the bottom of the pool cleaner coupled with the downward pressure created by the ejecting water that is being created will ensure that the pool cleaner remains in close contact to the floor or walls of the swimming pool.
The art depicts and describes numerous embodiments where said impeller pump motor is positioned—in an upright position or in an angled position—having impeller blades located remotely from of the pool cleaner inlet usually at a higher region within the hydraulic system path in the hollow body. The effect is an impeller pump that by means of the high-speed rotation of its plastic or non-rust metal made blades (at about 2600-3000 rpm) draws the water with sufficient force to pull the water through the filtering mechanism.
Such a hydraulic suction system is effective but has drawbacks:
a. The hollow body is never quite sealed from the surrounding pool water. The vacuum or negative internal pressure that is created and described above also draws unclean water from various openings in the pool cleaner body contour (wheel or brush areas, handle arrangements, venting/mechanical non-return valve elements etc.). This also causes air to be drawn into the hollow body, especially when climbing on the pool wall at waterline level. The vacuum and the suction force may thereby be reduced, at times, causing the pool cleaner to disengage from the waterline and to float uncontrollably on the water surface.b. It is necessary to employ a pump motor with propeller or impeller blades that have sharp edges and that are revolving at a very high speed. The propeller/impeller is potentially accessible to fingers or other objects through the inlets or outlets of the pool cleaner so that an incautious end user may insert a finger that will contact the sharp blades.c. The common upward position of the pump/impeller motor creates a high center of gravity. This is particularly problematic when in a climbing position on the pool wall where a high moment of force for wall disengagement is created by the pump motor location.d. In the hydraulic water path movement, the position of the impeller blades must be after the filtering mechanism in the hydraulic water flow path so that only filtered water will impact the revolving impeller blades. Any changes in this configuration i.e.: impeller blades before filtering element may cause blade breakage/dent that will reduce pump efficiency.e. The removal of the impeller/propeller from the upper area of the internal hollow body creates a space for introduction of a water outlet cylinder that will counteract revolving filer unit rotation torque forces with a water outlet spiral mechanism.